This invention relates to an improved process for refining and dewaxing crude vegetable oils and, more particularly, to a dilute lye and soda ash process in which efficient separation of undesirable waxes (about 60% to 90%) can be consistently achieved in refining crude oils such as sunflower, safflower, and corn oil.
In order to build superior taste into edible oil products, certain processing steps must be undergone.
Refining removes the major impurities, such as excess fatty acids and gummy substances, from the oil by treating it with dilute lye and soda ash. Usually, however, further treatment is necessary before the oil is ready for use.
Unwanted color is removed from the oil by bleaching. The oil is mixed with a special kind of clay, called "fuller's earth." The clay absorbs the colored material from the oil. The mixture is then filtered, allowing the oil to run out clear.
Unpleasant odors are removed by blowing super-heated steam through heated oil. Since the senses of taste and smell are closely linked, deodorization will also improve the flavor of the product.
The refined oil is further dewaxed to provide a refrigerator stable oil, i.e. one that does not cloud when chilled in a refrigerator.
U.S. Pat. Nos. 4,194,956 and 4,200,509 relate to the use of an electrofilter to dewax refined vegetable oils for refrigerator clarity. The refined oils are tempered first to nucleate, and then cooled to agglomerate the waxes before being electrofiltered.
Attempts have been made to refine and dewax crude vegetable oils using only one separation step. U.S. Pat. No. 3,943,155 to Young, Mar. 9, 1976, discloses a process for refining and dewaxing crude vegetable oils using only one separation step which removes both the hydrophilic and waxy components from the crude oil. An alkali and dewaxing treatment is employed to crude oil at a temperature of from about 15.degree. F. to about 45.degree. F.
U.S. Pat. No. 3,994,943, Gibble et al, Nov. 30, 1976, relates to dewaxing crude vegetable oils with a mixture of special surfactants. Crude oil tempering for wax nucleation and cooling for wax agglomeration is not taught in either the Young or Gibble et al patents.
Heretofore, efficient refining consistency in alkali wax removal from said crude edible oil has been erratic. Wax removal using an alkali process varied from almost 0% to about 90% removal using prior art techniques. It has now been discovered that the efficiency is dependent on crude oil temperatures and the time held at these temperatures before bringing the oils to a refining temperature for alkali treatment.
While the concept of combined refining and dewaxing as a single operation which would yield wax-free, refined sunflower seed oil is a desirable objective, as a practical matter there remains a need to refine oil using existing refining equipment and the alkali processes with only minimal modification.
It is, therefore, an object of the present invention to provide an improved process to dewax crude vegetable oils using the alkali process to reduce the wax load in a subsequent dewaxing operation.
It is also an object of this invention to provide a reliable refinery process which consistently removes about 60% to about 90% of the wax.
Other objects of this invention will become apparent in the light of the disclosure.